Health Assessment Document for Diesel Emissions - NSCEP | US ...
Health Assessment Document for Diesel Emissions - NSCEP | US ...
Health Assessment Document for Diesel Emissions - NSCEP | US ...
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1 monkeys there were no specific histopathological effects reported (see next section) although<br />
2 particle aggregates were reported in the distal airways, suggesting more small airway deposition.<br />
3 Gross (1981) exposed rats <strong>for</strong> 20 h!day, 5.5 days/week <strong>for</strong> 87 weeks to diesel exhaust<br />
4 containing 1.5 mg/m 3 particulate matter. When the data were normalized (e.g., indices expressed<br />
5 in units of airflow or volume <strong>for</strong> each animal by its own <strong>for</strong>ced expiratory volume), there were<br />
6 no apparent functionally significant changes occurring in the lungs at 38 weeks of exposure that<br />
7 might be attributable to the inhalation of diesel exhaust. After 87 weeks of exposure, functional<br />
8 residual capacity (FRC).and its component volumes (expiratory reserve [ER] and residual<br />
9 volume [RV]), maximum expiratory flow (MEF) at 40% FVC, MEF at 20% FVC, and FEV 0 _ 1<br />
1 0 were significantly greater in the diesel-exposed rats. An observed increase in airflow at the end<br />
11 of the <strong>for</strong>ced expiratory maneuver when a decreased airflow would be expected from the<br />
12 increased FRC, ER, and RV data (the typical scenario of human pulmonary disease) showed<br />
13 these data to be inconsistent with known clinically significant health effects. Furthermore,<br />
14 although the lung volume changes in the diesel-exposed rats could have been indicative of<br />
15 emphysema or chronic obstructive lung disease, this interpretation was contradicted by the<br />
16 airflow data, which suggest simultaneous lowering of the resistance of the distal airways.<br />
17 Heinrich et al. (1982) evaluated the pulmonary function ofrats exposed to a concentration<br />
18 of3.9 mg/m 3 particulate matter <strong>for</strong> 7 to 8 h!day, 5 days/week <strong>for</strong> 2 years. When compared with a<br />
19 control group, no significant changes in respiratory rate, minute volume, compliance, or<br />
20 resistance occurred in the exposed group (n,umber of rats per group was not stated).<br />
21 Hamsters (eight or nine per group) were exposed 8 h!day, 7 days/week, <strong>for</strong> 6 mo to<br />
22 concentrations of either about 6 mg/m 3 or about 12 mg/m 3 particulate matter (Vinegar et al.,<br />
23 1980, 1981a,b). Vital capacity, vital capacity/lung weight ratio, residual lung volume by water<br />
24 displacement, and C0 2 diffusing capacity de.creased significantly in hamsters exposed to<br />
25 6 mg/m 3 particulate matter. Static deflation volume-pressure curves showed depressed deflation<br />
26 volumes <strong>for</strong> diesel-exposed hamsters when volumes were corrected <strong>for</strong> body weight and even<br />
27 greater depressed volumes when volumes were corrected <strong>for</strong> lung weight. However, when<br />
28 volumes were expressed as percentage of vital capacity, the diesel-exposed hamsters had higher<br />
29 lung volumes at 0 and 5 em H 20. In the absence of confirmatory histopathology, the authors<br />
30 tentatively concluded that these elevated lung volumes and the significantly reduced diffusing<br />
31 capacity in the same hamsters were indicative of possible emphysematous changes in the lung.<br />
32 Similar lung function changes were reported in hamsters exposed at 12 mg/m 3 particulate matter;<br />
33 but detailed in<strong>for</strong>mation was not reported. It was stated, however, that the decrease in vital<br />
34 capacity was 176% greater in the second experiment than in the first.<br />
211/98 . 5-32 DRAFT--DO NOT CITE OR QUOTE